1. Field of the Invention
The present invention relates to temperature control systems for polymerase chain reactions generally and, more particularly, but not by way of limitation, to a novel temperature control system for polymerase chain reactions that is simple and affords an improved degree of control.
2. Background Art
Polymerase chain reaction (PCR) is a technique that is commonly used in genomic studies and other areas of biotechnology. It consists of taking biological samples through different temperature cycles multiple times to amplify the DNA. Typically, three different temperatures are used: T1, T2, and T3. The sample or samples are cycled through the three temperatures in a set sequence of times for each specific reaction protocol.
A typical protocol might be as follows: Hold the samples at 95 degrees Centigrade for five minutes to start the sequence. Then, sequentially, hold the sample(s) at 95 degrees Centigrade for 15 seconds, hold the samples(s) at 55 degrees Centigrade for 15 seconds, and hold the sample(s) at 72 degrees Centigrade for 30 seconds. This one-minute cycle is repeated 10 times. Then, sequentially, the samples are held at 89 degrees Centigrade for 15 seconds, held at 55 degrees Centigrade for 15 seconds, and held at 72 degrees Centigrade for 30 seconds. The second temperature sequence is repeated 20 times. The samples are then held at 72 degrees Centigrade for 10 minutes as a final step. The samples may then be held at four degrees Centigrade for a longer period of time until used.
The conventional method of conducting such protocols is to place multiple DNA samples in a 96-or 384-well microplate and then the plate is robotically switched between liquid baths, held at predetermined temperatures, for the indicated periods of time. In addition to being relatively expensive, such method suffers from not being able to control the ramp rate of temperature change.
Accordingly, it is a principal object of the present invention to provide a system for conducting PCR studies that is simple and economical.
It is an additional object of the invention to provide such a system that permits for accurate temperature control of the heat transfer medium in the system.
It is a further object of the invention to provide such a system that provides control of the ramp rate of temperature change between steps in the reaction protocol.
Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figures.
The present invention achieves the above objects, among others, by providing, in a preferred embodiment, a polymerase chain reaction temperature control system, comprising: a first tank into which a multiwell sample carrier may be placed; means to introduce first temperature controlled heat transfer medium into said first tank for a first predetermined length of time; and means to subsequently introduce at least a second second temperature controlled heat transfer medium into said first tank for at least a second predetermined length of time.